FILE (AS. leo!, 011G. fihala, lila, Ger. Pelle, °Church Slay. pita, file; connected ultimately with Lat. pingere, to paint, ()Church Slay. pisati, to write, Skt. pi*, to adorn). A steel instrument, with sharp ridges or teeth made by the indenta tions of a chisel, which is employed for cutting down and shaping metals or other hard sub stances. Abrading instruments having the gen eral characteristics of files arc doubtless very ancient. Indeed, the file may be said to be repre sented in its earliest and crudest form by the rough stones used by prehistoric man in shaping his implements of war and of the chase. Artifi cially made files are mentioned in the Old Testa ment in I. Sam. xiii. 21, and they are also mentioned in the Odyssey. These files were doubt less crude in form, and very inefficient in operation compared with the modern tool of the same name, but the fact that they were mentioned in these early writings is proof of the consideration in which they were held by the metal-workers of an cient times. The file has continued to remain one of the most useful of hand tools for working metals, and is to-day produced in enormous num bers and with an almost endless variety of forms and characteristics.
The modern file is a bar or rod of hardened steel having one end forged down to a long slim point or tang for insertion in a wooden handle, and the remainder of its length covered on one or all sides with serrations or teeth. A rasp is a species of file in which each tooth is an angular pit with a strong burr formed by a pointed punch, instead of a long furrow formed by a broad bladed chisel. Files and rasps are distinguished first by their length, which is always measured exclusive of the tang. second by their shape, and third by their cut, which has reference not only to the character, but also to the relative degrees of coarseness of the teeth. The length of a file is the distance between its heel, or part of the file where the tang begins, and the point or end opposite. in general the length of files bears no fixed proportion to either their width or their thickness. even though they be of the same gen eral shape or kind. By kind, in speaking of files, is meant the varied shapes or styles of files which are distinguished by certain technical names, as, for instance, flat, mill, and half-round. The various kinds of files are grouped according to the shape of their cross-section into quadrangu lar sections. circular sections, triangular sec tions, and miscellaneous sections. These sections are in turn subdivided, according to their general contour or outline, into taper and blunt. The File-teeth of any of the cuts described may be arranged so as to be spaced equidistant. or
they may be arranged so that the spacing varies term taper designates a file the point of which is more or less reduced in size, both in width and thickness, by a gradually narrowing section extending from one-half to two-thirds the length of the file from the point. The term blunt desig nates a file that preserves its sectional shape at different points of the file. When the latter arrangement is used the files are designated as increment cut. This form of cut is controlled by the Nicholson File Company, of Providence, R. 1., and Nicholson files only possess increment cut. The arrangement of the teeth in increment cut may be described as follows: (1) The rows of teeth are spaced progressively wider, from the throughout from point to tang. The cut of files is divided, with reference to the character of the teeth, into single cut, double cut, and rasp cut, and with reference to the coarseness of the teeth into rough, coarse, bastard, second cut, smooth, and dead smooth. The accompanying illustra tion show all of these cuts. The rough-cut file is one in which a single unbroken course of chisel cuts is made across its surface arranged. parallel to each other, but oblique to the centre line or axis of the file. The double-cut file has two courses of chisel cuts crossing each other, the second course with rare exceptions being finer than the first. Rasp-eut differs from single or double cut in the respect that the teeth are dis eonneeted from each other, each tooth being made by a single-pointed tool called a punch.
point toward the middle of the tile, by regular increments of spacing. (2.) This general law of spacing is modified by introducing. as the teeth are cut, an element of controllable irregularity of spacing. which irregularity is confined within maximum and minimum limits, but is not a reg Plat' increment or decrement. (3) The teeth are so arranged that the successive rows shall not be exactly parallel. hut cut slightly angularly with respect to each other, the angle or inclination be ing reversed during the operation of cutting as necessity requires.
The usual different sectional shapes of com mercial tiles are shown in the accompanying illus tration. In length such tiles range from three inches to twenty inches. Smaller tiles for jewel ers, die-sinkers, and watchmakers, and needle tiles are made of special material, and in various special sizes. As indicating the small sizes in which tiles are produced, it may be noted that the' smallest size of Nicholson round broach tile is but ,033 of an inch in diameter, and about one inch long.